The next time Ireland board a plane to make the short hop across the Irish Sea, it will be the real deal in 12 days' time when they fly to Cardiff for their World Cup opener against Canada.

The big show is within touching distance, but there is just one more hurdle to clear.

Joe Schmidt has being trying all week to put the phrase 'warm-up' out of the equation. His players are prepared at this stage, the important thing now is to perform.

Rob Kearney aside, he has gone full tilt for this clash with England in an attempt to have his core players battle-hardened and match-ready.

Cian Healy is also kept on ice, but this team has a familiar feel to it and the coach wants his combinations to click into gear.

The end result will fade to irrelevance soon, but victory at Twickenham is never to be sniffed at. Schmidt knows that his side can use tomorrow's game as a launchpad.

Much has been said about Ireland's preparation, but now they need to ramp up to match-readiness.

The World Cup schedule is kind in that they have clashes with Canada, Romania and Italy before taking on France on October 11 and managing that peak has been front and centre of Schmidt's plans.

So far, his extended squad have beaten Wales and Scotland before Warren Gatland's side gained revenge last weekend. But now it is almost time for full throttle.

"What we did try to do was gauge who's a bit more fatigued than others," Schmidt said of his selection. "It's been a big block of nine weeks of work and it's just trying to balance a little bit of game time, a little bit of recovery, so that we get guys in their very best condition in two weeks' time.

"It's very challenging because it's not something I've done before. The advantage is that I've got to know the players quite well.

"Some players will go out and play really well fresh, and other players need a couple of games and you have to keep them ticking over. It's just about getting that balance right.

"We've also tried to mix up a few combinations because with so many congested big games together, we may be forced to make some changes and we just want to feel that we're able to mix and match.

"Keith Earls, while he's gone through the return-to-play protocols, we thought it was prudent to leave him out and he has freshened up nicely. Luke Fitzgerald, as well, he trained fully during the week. We just felt it was prudent to leave him out.

"And then we put the other guys together and decided, right, who needs a bit of game time and who doesn't?

"Who plays really well fresh and do we keep him fresh for the tournament? It's just getting that mix is part of the challenge."

By selecting so many perceived front-liners, there is much to mull over at Twickenham tomorrow.

How will Devin Toner and Peter O'Mahony respond to Iain Henderson throwing down the gauntlet last weekend? Can Ireland expand their attacking game?

This will be a good gauge of Ireland's physicality as they go toe-to-toe with Stuart Lancaster's men.

"I don't think you ever go to Twickenham for a warm-up game," Schmidt said. "It's very much a hot-bed from the start. I've no doubt that they're looking to rebound as we will be.

"We felt a little bit unlucky last week and a lot of what we did put us in a good field position to do a little bit better now.

"We've just got to make sure that we finish a few things this week. But there's no tougher team to break down defensively than the English.

"You might have the ball, but they have the momentum. It does make it a pretty tough day, so we're going to have to be really accurate around the breakdown."

Individually, the decision not to play Rob Kearney hands Simon Zebo the No 15 shirt, but conversely allows Dave Kearney another opportunity to impress on the left wing.

Although Schmidt praised Zebo's ability to cover full-back, he did point out a defensive glitch against Scotland and the Munster flyer needs to be on his game. The coach downplayed a bruised knee suffered by the elder Kearney.

Most of those starting can be confident of being back on the biggest stage against Canada later this month.

The important thing is ensuring they're in peak condition when they do so.